Winters are cold, and ice can easily form in water tanks of some cars, such as recreational vehicle (RVs). Thus, an electric heating pad is used to prevent ice formation around the water tank. The electric heating pad heats the water tank and prevents the water tank from ice formation after the electric heating is electrified. A typical electric heating pad includes a substrate, a heating layer, and a leading wire connected to the heating layer. The leading wire is directly soldered and fixed on the heating layer. The leading wire is easily separated from the heating layer after undue force acts on the leading wire during use of the electric heating pad, which causes the electric heating pad not to work.